Renewal of alveolar epithelium in the rat following exposure to NO2

Am J Pathol. 1973 Feb;70(2):175-98.


This research was undertaken to study the kinetics of Type 2 cell division and the fate of the Type 2 sister cell following exposure to NO(2). To accomplish this, male rats were exposed to NO(2). Dividing cells were labeled with (3)H-TdR and studied with autoradiographic technics in the light and electron microscopes for up to 72 hours after labeling. The kinetics of cell division were determined from a curve constructed from the percent of labeled mitotic figures. The fate of the Type 2 sister cells was determined by studying tissues at 24, 48 and 72 hours after labeling with (3)H-TdR. The results show that Type 2 cells may divide and the sister cells transform into Type 1 cells. These data support an interpretation of the mechanism for cell renewal of the alveolar epithelium in which Type 2 cells are the progenitor cells for Type 1 cells.

MeSH terms

  • Animals
  • Autoradiography
  • Basement Membrane / cytology
  • Cell Division / drug effects*
  • Environmental Exposure
  • Epithelial Cells
  • Epithelium / drug effects
  • Histological Techniques
  • Kinetics
  • Male
  • Microscopy, Electron
  • Nitrogen Dioxide / pharmacology*
  • Pulmonary Alveoli / cytology*
  • Pulmonary Alveoli / drug effects
  • Rats
  • Thymidine / metabolism
  • Time Factors
  • Tritium


  • Tritium
  • Nitrogen Dioxide
  • Thymidine